# http://www.graphviz.org/content/cluster digraph G { graph [fontname = "Handlee"]; node [fontname = "Handlee"]; edge [fontname = "Handlee"]; bgcolor=transparent; subgraph cluster_0 { style=filled; color=lightgrey; node [style=filled,color=pink]; "publisher 1" -> "broker"[label="publish to c1"] "publisher 1" -> "broker"[label="publish to c2"] "publisher 2" -> "broker"[label="publish to c1"] "publisher 3" -> "broker"[label="publish to c2"] "subscriber 1" -> "broker"[label="subscribe to c1"] "subscriber 2" -> "broker"[label="subscribe to c2"] "broker" -> "subscriber 1"[label=""] "broker" -> "subscriber 2"[label=""] label = "*Publisher / Subscriber broker*"; fontsize = 20; } broker [shape=Mdiamond]; }